Even if animals were less similar to us than they are, we would still owe them a duty of fellow-feeling, simply because they are alive. There is a certain respect, and a general duty of humanity, that attaches us not only to animals, who have life and feeling, but even to trees and plants. We owe justice to men, and mercy and kindness to other creatures that may be capable of receiving it. There is some relationship between them and us, and some mutual obligation.
